International Journal of Modeling, Simulation, and Scientific Computing

Combined cycle power plant (CCPP) usually plays an important role in balancing byproduct gas generation and consumption in integrated iron and steel plant. The low heat value fuel gases, such as blast furnace gas (BFG) or mixed gas with Coke oven gas (COG) and BFG, are preferred to be used in high-efficient CCPP for power generation. In practice, the general heat value of mixed gas can be set in the range of 3500–4400kJ/Nm³. This paper presents a methodology to simulate operating parameters of CCPP with BFG. A generic model of gas turbine with open loop stage cooling employing air is used to simulate the performance of gas turbines cycle under different compressor pressure ratios and turbine inlet temperatures (TIT). The isentropic efficiencies for gas compressor and gas turbine are supposed to be constants and set corresponding to published industrial experience. The steam cycle is composed of classical double-pressure heat recovery steam generator (HRSG) and steam turbines according to gas turbine outlet temperature. Specific work, gas turbine cycle efficiency, cogeneration thermal efficiency and coolant air flow requirements are evaluated to find the optimal compressor pressure ratio and TIT. The research results are useful to select the optimum operating parameters of CCPP with BFG. Performance features were estimated with the help of compression ratios 12.5–20 and combustor exit temperature 1150–1350${}^{\circ }$C.

Most of the vector-borne diseases show a clear dependence on seasonal variation, including climate change. In this paper, we proposed a nonautonomous mathematical model consisting of a periodic system of nonlinear differential equations. In the proposed model, the realistic functional forms for the different temperature-dependent parameters are considered. The autonomous system of the proposed model is also analyzed. The nontrivial solution of the autonomous model is locally asymptotically stable if $R_0<1$. It is shown that a unique endemic equilibrium point of the autonomous model exists when $R_0>1$ and proved that endemic solution is linearly stable when $R_0>1$. The nonautonomous model is shown to have a nontrivial disease-free periodic state, which is globally asymptotically stable whenever temperature-dependent reproduction number is less than unity. It is observed that a unique positive endemic periodic solution of the nonautonomous system exists only when a temperature-dependent reproduction number greater than unity, which makes for the persistence of the disease. Numerical simulation has been carried out to support the analytical results and shows the effects of temperature variability in the life span of mosquitoes as well as the persistence of the disease.

In the process of complex product design, modeling in different fields and different disciplines is often involved. Designers often face many different development kits, platforms, and theories, among which significant differences exist. Especially in the process of algorithm-hardware implementation, it is necessary to have mastery of the knowledge including algorithm, hardware, circuit, and system engineering. In this paper, a modeling method of algorithm-hardware based on SysML is proposed to reduce the difficulty of algorithm-hardware modeling. By using the method, the designers who do not know the knowledge of hardware can also easily build the algorithm-hardware model. In this method, a method of graphical system modeling based on SysML is used, where the elements of the algorithm-hardware model are described by SysML graphical models. Then, the SysML graphical models are converted to Very-High-Speed Integrated Circuit Hardware Description Language. At last, a detecting algorithm of random number is complemented by the modeling method in this paper and the simulation results are presented at the conclusion.

People who live in low-income and hard-to-reach regions are usually the most affected ones by high incidences of arboviral diseases, increasing morbidity and mortality rates, and public health costs. We present the modeling of hardware and software components of an unmanned aerial vehicle (UAV) system by mathematical tools, focusing on monitoring foci of arboviral diseases transmitted by Aedes aegypti mosquito, e.g., Zika, Chikungunya, and Dengue. We used restriction equations and the colored Petri nets formal modeling language to represent the flight dynamics and the software components of the system, respectively. We evaluated the specification of desired behaviors of the monitoring system using simulations and the model checking technique. The results showed the completeness and correctness of the specification. The design of such a system is challenging due to the potential risks to people and the environment. Therefore, this study provides insights into the development of an UAV system for such an application scenario. The monitoring system has the potential of improving the efficiency in identifying foci of arboviral diseases.

A mathematical model is proposed in this paper to study the transmission and control of COVID-19. The mathematical model is formulated using system of nonlinear ordinary differential equations. The model includes disease-related parameters such as contact rate, disease-induced death rates, immigration rate and transition rates along with parameters for control measures such as implementation of social distancing practices, isolation and quarantine rates. From the stability analysis of the model, it is shown that if the social distancing is practiced by the large number of susceptible population, then the disease will not spread, and it may eventually die out. Further, it is derived from the analysis of the model that if most of the infected populations are isolated or quarantined, then the spread of the disease can be eventually controlled. However, from the analysis of the model, it is observed that if there is constant immigration of asymptomatic infected persons, then the disease will continue to spread and will remain pandemic. For controlling the disease, two more parameters, that is, vaccination and testing rates, are introduced in the original mathematical model and from the numerical analysis of this model, it has been shown that the control strategy involving vaccination and testing in combination can have synergistic effect for minimizing the COVID-19 infected cases.

The total hip replacement is the only approved procedure for restoring a degenerated hip joint through operation. The life span of a prosthesis could depend on the geometry and material properties of the implant. This study aims to analyze the biomechanics of the carbon/polyetheretherketone (PEEK) composite prosthesis having three different fiber ply configurations compared to traditional stainless steel (SS) ones. The implant-bone system was established and subjected to a load from the head of the femur and abductor muscle sides. The stresses and strains in the implant-bone systems were calculated and compared. The results revealed lower stresses and strains in composite prostheses compared to SS ones. The fiber ply orientation of the carbon/PEEK composite prosthesis is shown to be a key asset in stress and strain distribution of the 13 implant-bone systems. The fiber plies which orientated multidirectionally with −45 and +45 degrees exhibited uniform stress and strain distributions. The results suggested the advantage of using composite prostheses in implant designs as they not only invoke lower stresses and strains in the implant-bone system but also amplify the life span of implants in the body.

Online portfolio selection and simulation are some of the most important problems in several research communities, including finance, engineering, statistics, artificial intelligence, machine learning, etc. The primary aim of online portfolio selection is to determine portfolio weights in every investment period (i.e., daily, weekly, monthly, etc.) to maximize the investor’s final wealth after the end of investment period (e.g., 1 year or longer). In this paper, we present an efficient online portfolio selection strategy that makes use of market indices and benchmark indices to take advantage of the mean reversal phenomena at minimal risks. Based on empirical studies conducted on recent historical datasets for the period 2000 to 2015 on four different stock markets (i.e., NYSE, S&P500, DJIA, and TSX), the proposed strategy has been shown to outperform both Anticor and OLMAR — the two most prominent portfolio selection strategies in contemporary literature.

Our endocrine system is not only complex, but is also enormously sensitive to the imbalances caused by the environmental stressors, extreme weather situation, and other geographical factors. The endocrine disruptions are associated with the bone diseases. Osteoporosis is a bone disorder that occurs when bone mineral density and bone mass decrease. It affects women and men of all races and ethnic groups, causing bone weakness and the risk of fractures. Environmental stresses are referred to physical, chemical, and biological factors that can impact species productivity. This research aims to examine the impact of environmental stresses on bone diseases like osteoporosis and low bone mass (LBM) in the United States (US). For this purpose, we use an artificial neural network model to evaluate the correlation between the data. A multilayer neural network model is constructed using the Levenberg–Marquardt training algorithm, and its performance is evaluated by mean absolute error and coefficient of correlation. The data of osteoporosis and LBM cases in the US are divided into three groups, including gender group, age group, and race/ethnicity group. Each group shows a positive correlation with environmental stresses and thus the endocrinology.

Background: CAR-T cells are chimeric antigen receptor (CAR)-T cells; they are target-specific engineered cells on tumor cells and produce T cell-mediated antitumor responses. CAR-T cell therapy is the “first-line” therapy in immunotherapy for the treatment of highly clonal neoplasms such as lymphoma and leukemia. This adoptive therapy is currently being studied and tested even in the case of solid tumors such as osteosarcoma since, precisely for this type of tumor, the use of immune checkpoint inhibitors remained disappointing. Although CAR-T is a promising therapeutic technique, there are therapeutic limits linked to the persistence of these cells and to the tumor’s immune escape. CAR-T cell engineering techniques are allowed to express interleukin IL-36, and seem to be much more efficient in antitumoral action. IL-36 is involved in the long-term antitumor action, allowing CAR-T cells to be more efficient in their antitumor action due to a “cross-talk” action between the “IL-36/dendritic cells” axis and the adaptive immunity. Methods: This analysis makes the model useful for evaluating cell dynamics in the case of tumor relapses or specific understanding of the action of CAR-T cells in certain types of tumor. The model proposed here seeks to quantify the action and interaction between the three fundamental elements of this antitumor activity induced by this type of adoptive immunotherapy: IL-36, “armored” CAR-T cells (i.e., engineered to produce IL-36) and the tumor cell population, focusing exclusively on the action of this interleukin and on the antitumor consequences of the so modified CAR-T cells. Mathematical model was developed and numerical simulations were carried out during this research. The development of the model with stability analysis by conditions of Routh–Hurwitz shows how IL-36 makes CAR-T cells more efficient and persistent over time and more effective in the antitumoral treatment, making therapy more effective against the “solid tumor”. Findings: Primary malignant bone tumors are quite rare (about 3% of all tumors) and the vast majority consist of osteosarcomas and Ewing’s sarcoma and, approximately, the 20% of patients undergo metastasis situations that is the most likely cause of death. Interpretation: In bone tumor like osteosarcoma, there is a variation of the cellular mechanical characteristics that can influence the efficacy of chemotherapy and increase the metastatic capacity; an approach related to adoptive immunotherapy with CAR-T cells may be a possible solution because this type of therapy is not influenced by the biomechanics of cancer cells which show peculiar characteristics.

A stochastic SIR influenza vertical transmission model is examined in this paper where vaccination and an incidence rate that is not linear are considered. To determine whether testosterone regulates lower sintering HPA axis function in males, we used a stochastic SIR epidemic procedure with divergent influences on ACTH and cortisol. The suppressive effects on cortisol can be attributed to a peripheral (adrenal) locus. Following that, we came to the conclusion that experimental solutions have been discovered and the requisite statistical findings have been examined. Finally, we deduce that the given mathematical model and the results are relevant to medical research. In the future, this research can be further extended to simulate more results in the medical field.

In this paper, we propose a three-species model consisting of two competing (prey and nonprey) species and a predator species. Here, nonprey species are not included in the predator’s food choice. The competition process follows Holling type II competitive response to interference time. Basic results include the stability of the system. First, it is established that an increasing number of interference time stabilizes the system. Second, it is shown that the interference time has an impact on the predator equilibrium density. Third, we develop the criterion of persistence of all the species. It is also shown that the system may not be persistent when multiple steady states appear. We examine the global stability of the coexistence equilibrium point. Numerical experiments are carried out to understand the analytical outcomes.

The paper is devoted to simulating the impact of a thermal shock on a thin homogeneous plate in the ANSYS package. The assessment of the stress–strain state is carried out and the dynamics of changes in the temperature field of the plate is determined. The obtained results were compared with the data of other authors and can be used when taking into account the thermal shock of large elastic elements of spacecraft.

With the accelerated development of agricultural intelligence and mechanization, the traditional premixed pesticide mixing method has been unable to meet people’s needs for safe, environmental and efficient agricultural production. Therefore, an in-depth study on a variety of new pesticide mixing methods has been conducted at home and abroad. The single-stage on-line jet mixing method has been increasingly used because of its advantages of safety and high efficiency, which, however, proved to have some disadvantages such as difficulty in controlling the pesticide mixing ratio and poor mixing uniformity. In this experiment, a set of double-stage online jet mixing apparatus was designed to solve some shortcomings of single-stage online jet mixing apparatus, and the influence of jet nozzle parameters in the main jet mixing apparatus and the radiation flow mixing apparatus on the final pesticide mixing effect were studied for this apparatus, and the most appropriate jet nozzle parameters were selected.